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GHSA-VC3M-HCQ5-8VHR

Vulnerability from github – Published: 2026-05-05 18:33 – Updated: 2026-05-08 15:31

Details

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reset register ID for BPF_END value tracking

When a register undergoes a BPF_END (byte swap) operation, its scalar value is mutated in-place. If this register previously shared a scalar ID with another register (e.g., after an r1 = r0 assignment), this tie must be broken.

Currently, the verifier misses resetting dst_reg->id to 0 for BPF_END. Consequently, if a conditional jump checks the swapped register, the verifier incorrectly propagates the learned bounds to the linked register, leading to false confidence in the linked register's value and potentially allowing out-of-bounds memory accesses.

Fix this by explicitly resetting dst_reg->id to 0 in the BPF_END case to break the scalar tie, similar to how BPF_NEG handles it via __mark_reg_known.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-43070"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-05T16:16:16Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reset register ID for BPF_END value tracking\n\nWhen a register undergoes a BPF_END (byte swap) operation, its scalar\nvalue is mutated in-place. If this register previously shared a scalar ID\nwith another register (e.g., after an `r1 = r0` assignment), this tie must\nbe broken.\n\nCurrently, the verifier misses resetting `dst_reg-\u003eid` to 0 for BPF_END.\nConsequently, if a conditional jump checks the swapped register, the\nverifier incorrectly propagates the learned bounds to the linked register,\nleading to false confidence in the linked register\u0027s value and potentially\nallowing out-of-bounds memory accesses.\n\nFix this by explicitly resetting `dst_reg-\u003eid` to 0 in the BPF_END case\nto break the scalar tie, similar to how BPF_NEG handles it via\n`__mark_reg_known`.",
  "id": "GHSA-vc3m-hcq5-8vhr",
  "modified": "2026-05-08T15:31:15Z",
  "published": "2026-05-05T18:33:25Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43070"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0d15c3611a2cc5d08993545d4032055ae10ae2c1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a17443af874229408ce6b78e2c8a2b5adeb4b7d8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a3125bc01884431d30d731461634c8295b6f0529"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-43070 (GCVE-0-2026-43070)

Vulnerability from cvelistv5 – Published: 2026-05-05 15:23 – Updated: 2026-08-05 12:25

Title

bpf: Reset register ID for BPF_END value tracking

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Reset register ID for BPF_END value tracking When a register undergoes a BPF_END (byte swap) operation, its scalar value is mutated in-place. If this register previously shared a scalar ID with another register (e.g., after an `r1 = r0` assignment), this tie must be broken. Currently, the verifier misses resetting `dst_reg->id` to 0 for BPF_END. Consequently, if a conditional jump checks the swapped register, the verifier incorrectly propagates the learned bounds to the linked register, leading to false confidence in the linked register's value and potentially allowing out-of-bounds memory accesses. Fix this by explicitly resetting `dst_reg->id` to 0 in the BPF_END case to break the scalar tie, similar to how BPF_NEG handles it via `__mark_reg_known`.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/a17443af874229408…
https://git.kernel.org/stable/c/0d15c3611a2cc5d08…
https://git.kernel.org/stable/c/a3125bc01884431d3…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 4c03342e5ac532fb34d13a7b51dd7261dfc48963 , < a17443af874229408ce6b78e2c8a2b5adeb4b7d8 (git) Affected: d00ce96623a69a100ad79675d0e85fda3c50d89b , < 0d15c3611a2cc5d08993545d4032055ae10ae2c1 (git) Affected: 9d21199842247ab05c675fb9b6c6ca393a5c0024 , < a3125bc01884431d30d731461634c8295b6f0529 (git)
Linux	Linux	Affected: 6.18.17 , < 6.18.21 (semver) Affected: 6.19.7 , < 6.19.11 (semver)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/verifier.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a17443af874229408ce6b78e2c8a2b5adeb4b7d8",
              "status": "affected",
              "version": "4c03342e5ac532fb34d13a7b51dd7261dfc48963",
              "versionType": "git"
            },
            {
              "lessThan": "0d15c3611a2cc5d08993545d4032055ae10ae2c1",
              "status": "affected",
              "version": "d00ce96623a69a100ad79675d0e85fda3c50d89b",
              "versionType": "git"
            },
            {
              "lessThan": "a3125bc01884431d30d731461634c8295b6f0529",
              "status": "affected",
              "version": "9d21199842247ab05c675fb9b6c6ca393a5c0024",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/verifier.c"
          ],
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          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "6.18.21",
              "status": "affected",
              "version": "6.18.17",
              "versionType": "semver"
            },
            {
              "lessThan": "6.19.11",
              "status": "affected",
              "version": "6.19.7",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.21",
                  "versionStartIncluding": "6.18.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.11",
                  "versionStartIncluding": "6.19.7",
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                }
              ],
              "negate": false,
              "operator": "OR"
            }
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      ],
      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reset register ID for BPF_END value tracking\n\nWhen a register undergoes a BPF_END (byte swap) operation, its scalar\nvalue is mutated in-place. If this register previously shared a scalar ID\nwith another register (e.g., after an `r1 = r0` assignment), this tie must\nbe broken.\n\nCurrently, the verifier misses resetting `dst_reg-\u003eid` to 0 for BPF_END.\nConsequently, if a conditional jump checks the swapped register, the\nverifier incorrectly propagates the learned bounds to the linked register,\nleading to false confidence in the linked register\u0027s value and potentially\nallowing out-of-bounds memory accesses.\n\nFix this by explicitly resetting `dst_reg-\u003eid` to 0 in the BPF_END case\nto break the scalar tie, similar to how BPF_NEG handles it via\n`__mark_reg_known`."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The vulnerable verifier logic is reached by a local attacker through the bpf() syscall when loading an eBPF program, not by remote packets directly.\nAC:L - The attacker controls the BPF bytecode and can construct the shared scalar-ID plus BPF_END pattern; there is no race or external timing condition required beyond program execution.\nPR:L - A basic local user can reach this in deployments with unprivileged BPF enabled or delegated BPF token capability; if uncertain between requiring CAP_BPF and unprivileged reachability, the higher-severity PR:L is appropriate.\nUI:N - No victim action is required; the attacker loads and triggers the BPF program themselves.\nS:U - The impact is within the kernel security authority, matching a standard local kernel privilege escalation rather than a cross-scope escape.\nC:H - The verifier can incorrectly validate out-of-bounds memory accesses, and such memory corruption/read primitives can expose arbitrary kernel memory.\nI:H - The demonstrated bad bounds propagation permits out-of-bounds writes through BPF pointer arithmetic, which is defensibly exploitable for kernel memory corruption or code execution.\nA:H - Out-of-bounds kernel memory access can crash or panic the kernel even if not fully exploited."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:25:43.557Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/a3125bc01884431d30d731461634c8295b6f0529"
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      ],
      "title": "bpf: Reset register ID for BPF_END value tracking",
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      }
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43070",
    "datePublished": "2026-05-05T15:23:28.819Z",
    "dateReserved": "2026-05-01T14:12:55.982Z",
    "dateUpdated": "2026-08-05T12:25:43.557Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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